Variable tuning condenser



Oct. 29, 1929.

H. SPONGBERG VARIABLE TUNING CONDENSER Filed Sept. 21. 1927 3 Sheets-Sheet jigii.

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Oct. 29, 1929. H SPONGBERG 1,733,281

VAR IABLE TUNING CONDENSER Filed Sent. 21, 1927 3 Sheets-Sheet 2 I E I 'Zfi a. 59

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Oct 1929- H. SPONGBERG VARIABLE TUNING CONDENSER :5 Sheets-Sheet 6 Filed Sept. 21, 1927 1 VENTOR. Jpo/y ov ZT-TOI'QNEYS.

Patented Oct. 29, 1929 UNITED STATES PATENT OFFICE HENRY SPONGBERG, F LOOMIS, NEBRASKA VARIABLE TUNING CONDENSER Application filed September 21, 1927. Serial No. 221,058.

tially eliminate interference of broadcast programs with one another, the invention contemplatingthe provision of a condenser which may be so ad'ustedas to permit the tuning in of a broa cast station to the exclusion of other stations broadcasting on approximately the same wave length. I

-Another object of the invention is to provide a variable condenser so constructed that it maybe adjusted as to render the receiving 1 apparatus, of which it constitutes a part, more sharply tuned than is possible by the use of condensers of theordinary construction.

Another object of the invention is to provide a variable condenser embodying two condenser units the combined capacity of which is-equal to the proper capacity for the particular radio frequency transformer with which the condenser is associated, in combi- 95 nation with means whereby the units may be independently accurately ad'usted to provide for a finer degree of a justment than is possible with the use of the ordinary types of variable condensers.

Another object of the invention is toprovide, in a variable condenser embodying two condenser ,units and Vernier means for adjusting the units independently of each other, novel'means whereby the units may be simultaneously adjusted, where a quick adjust Figure 2 is a vertical transverse sectional view taken substantially on the line 2-,2 of Figure 3 looking in the direction indicated by the arrows and illustrating, in elevation, the forward head of the condenser and the manner of mounting the frame upon the panel,

Figure 3 is a vertical front to rear sectional view taken axially through the condenser mounted upon the panel,

Figure 4 is a vertical transverse sectional view through the condenser taken substantially on the line 44 of Figure 3 looking in the direction indicated by the arrows,

Figure 5 is a top plan view of the condenser mounted upon the panel,

Figure 6 is a vertical transverse sectional view taken substantially on the line 6-6 of Figure 3 looking in the direction indicated by the arrows,

- Figure 7 is a sectional view illustrating one of the Vernier shafts and the means for mounting the same.

The variable condenser embodyin the invention is, of course, to be employe in connection with any of the well-known types of radio fre uency transformers and inasmuch as it is a apted for universal use in connection with such transformers and is wired thereto in the usual manner, the drawings have been restricted to the condenser alone, the panel upon which the, condenser is mounted, and which panel is indicated by the numeral 1, 'bein however illustrated in the drawings in o er to better exemplify the construction and operation of the condenser. The body structure of the condenser includes a front head 2, a \rear head 3, and an intermediate head 4, these heads-,bein suitably spaced and of any suitable ins sting material such for example as bakelitc, the heads being maintained in proper spaced relation through the medium of rods .5 whichare fitted through openings formed atsuitable intervals in the ripheral portions of the heads 2, 3 and 4, th: rods being provided each at one end with a head 6 to' bind against the rear face of the head 3 and at its other end being threaded asof a plurality of threaded openings formed in the peripheral portion of the head 2, the intermediate portion of each rod 5 extending through a respective one of a plurality of openings 8 formed in the peripheral portion of the intermediate head 4. These rods 5 extend likewise through the usual openings 9 formed in the peripheral portions of the fixed plates of the condenser and through spacing collars or washers 10 which are interposed between the fixed plates and which serve to properlyspace the same with respect to one another. As before stated the condenser, embodying the invention, embodies two condenser units and one of these units is indicated in general in the drawings by the reference letter A and the other unit in general by the reference letter B, each unit in cluding a group of the fixed condenser plates, and the said fixed plates of the unit A being indicated by the numeral 11 and those of the unit B by the numeral 12. The movable plates of the two condenser units A and B are indicated respectively by'the numerals 13 and 14, and at this point it may be stated that each condenser unit embodies anequal number of fixed and movable plates, and the plates arev of the usual substantially semicircular form and are of uniform dimensions, so that each condenser unitis of the same capacity. As an example of the invention, and assuming that the radio frequency trans former requires a .0005 condenser, each condenser unit A and B will be of .00025 microfarad capacity.

The rotors of the two condenser units are mounted upon concentrically arranged shafts, and one of these shafts is indicated, b the numeral 15 and is journalled at one en in a suitable bearing 16 arranged within an opening in the head 3. A contact element 17 is secured through the rear side of the head 3 and contacts the rear end of the shaft 15, and, to this-contact element there may be connected one of the wires leading to the radio frequency transformer. The numeral 18 indicates a sleeve which is exteriorly threaded atone end and fitted into an opening 19 formed in theintermediate head 4 near the upper margin thereof, lock nuts 20 being preferably fitted onto this" end of the sleeve and adjusted to bind against the opposite faces of the said head 4. The said sleeve 18 is fitted onto a reduced portion 21 of, the shaft 15, and fitted rotatably on the sleeve ,18 is a sleeve shaft 22 u "on which are mounted the rotor plates 13 o the condenserunit A, these plates being suitabl spaced by washers 23 like- -wise arrange ,on the sleeve shaft, and thus properly positioned between the stator plates 11 of thesaid' unit. A fiber gear'24 is provided with aninteriorly threaded hub 25 fitted onto a threaded portion of the sleeve shaft 22, and a nut 26 is fitted onto the exteriorly threaded rear end portion of said shaft, the said rotor plates 13 being in this manner fixed upon the said sleeve shaft 22. In order that a Vernier adjustment of the rotor plates 13 may be effected, a shaft 27 is journalled in a bushing 28 which is fitted into an opening 29 formed in the panel 1 and secured in place by a nut 30 which is threaded onto the inner end of the bushing and bears against an ear 31 formed at the periphery of the head 2 and through which the innersend of the bushing extends. The bushing 28 is provided at its outer or forward end with an approximately circular head 32 which bears against the outer face of a seating rim or flange 33 formed at the periphery of the cylindrical wall 34 of a housing 35 for the dials of the condenser, which dials will presently be more specifically described. A

fiber pinion 36 is fixed upon the shaft 29 at the inner end of the bushing 28 and meshes with the fiber gear 24. The inner end of the shaft 27 is journalled in an ear 37 which is provided at the lower edge of the intermediate head 4, anda collar 38 is fixed upon the shaft and engages against the forward side ofsaid ear so as to revent inward or rearward displacement of the shaft 27, the engagement of the pinion36 against the inner end of the bushing 28, preventin forward or outward displacement of sai shaft. A knurled finger knob 39 is fixed upon the outer end of the shaft 27 and provides means whereby theshaft may be rotated so asto impart rotary motion to the pinion 36 and to the gear 24 to effect rotary adjustment of the rotor plates 13 of the condenser unit A.

I In order that the rotor. of the condenser unit B may be adjusted, a fiber gear 40 is fixed up onthe shaft 15 inwardly of the bearing 16 in the head 3, and a shaft 41 corresponding 'tothe shaft 27 is rotatably journalled in a bushing 42 corresponding to the bushing 28 and mounted 'in the same manner as the said bushing28 and held in place u n the panel by a nut.43 threaded thereon. he said shaft 41 extends through an sun 44 likewise provided at the lower edge of the head 4, and is mounted at its inner or rear end in a suitable bearing-45 upon the head 3, a pinion 46 being fixed upon the said shaft 41-and meshing with the gear 40, and a knurled finger knob 47 being fixed upon the forward end of the shaft 41 whereby rotary motion may be imparted to the shaft to rotate the pinion 46 and impart rotary motion to the gear 40 and thus effect rotary adjustment of the rotor of the condenser unit B. The nut 43 which is fitted to the bushing 42, is tightened to bind against an ear 48 likewise formed at the lower edge of the head 2 and at a point opposite the ear 31, it being understood that in this manner the lower portion of'the said head 2 is secured to the inner face of the panel. Bolts 49 are izs through the panel 1 and through ears formed at the upper side .of the head 2 at spaced points, nuts 51 being threaded onto t e said bolts to bind against the said ears 50 and thus secure the upper portion of the head 2' to the inner face of the panel.

The sleeve shaft 22 is extended forwardly through a bearing 52 arranged within an opening formed centrally in the head2, and likewise through an opening 53 formed in the panel 1, and a dial' 54 is provided upon this end of the shaft and is fixed with respect thereto. The said dial 54 is in the form of a circular disk which is provided upon its forward or outer face with a peripheral relatively wide flange 55 upon the face of which, throu hout one-half the circumference of the aid ange,,is provided a scale 56 comprising scale marks ranging from 100 to 200.

A flat circular dial 57 is fixed upon the reduced rtion 21 of the shaft 15 in front of the dia 54and is positioned withinthe bounds of the flange 55 of the said dial 54, as clearly shown in Figures 1,3 and f the drawings,

the dials being however sufficiently spaced to insure'against mutual contact. The dial 57 is provided upon its face and at isperiphery with a scale 58 ranging from 0 to 100 and the said scale extends, as in the instance of the scale 56 for one-half the circumference of the periphery of, the dial. -The housing 35 for the dials 54 and 57 is formed in the upper oortion of its front wallwithanarcuate sight opening 59 through which both of the scales 56 and 58 may be viewed, in the rotative adjustment of the dials, and an indicating element 60 such as a thin web of metal or a small wire.

may be positioned to span the sight opening 59 intermediate the ends thereof, and constitutes an indicator into registration with which the scale marks of the scales '56 and 58 may be brought.

At this point it will be understood that bv manipulatmg the knurled finger knobs 39 and 47, the rotors of the condenser units A and Bflmay beindependently adjusted with great accuracy, and, due to the division of the otor and stator plates of the condenser into two groups and the provision of means for independently adjusting the rotors of the two units. the'receiving set of which the condenser constitutes a part, maybe very sharply and accurately tuned; In other words, when the rotors ofthe two condenser units havebeen adjusted toa definite wave length to receive the broadcast. waves from one station, and it is found that another station is interfering, he rotor of the condenser unit -B, for example, may be slightly adjusted so as. to more accurately tune the set and eliminate the interfering stations.

Inasmuch as it will be desirable, at times, .0 effect a more rapid adjustment of the rotors of the condenser units, than can be effected by the adjustment of the vernier knobs 39 and 47, means is provided which will now be described. It will be observed by reference to Figure 3 of the drawings that the forward end of the shaft 21 is extended somewhat beyond the dial 57, and a sleeve 61 isv fitted onto this extension of the shaft 21 and carries, at its inner end, which end abuts against the dial 57 at the center thereof, a collar 62 through which and the said end of the sleeve is, threaded a screw 63 which bears against the reduced pdrtion 21 of the shaft 15 and secures .the sleeve upon the extension of this portion of the shaft. The front wall of the lar 67 is fitted onto the sleeve 61 and is arranged within the finger knob 25 and held in place by a set screw 68, and a compression spring 69 is arranged within the knob and bears at one end against the said collar 67 and at its other end against the collar 62, the spring normally holding the knob shifted outwardly through the opening 64 and with its flange 66 hearing, as stated, against the inner side of the front wall of the housing 35.

Four openings 70 are formed in the dial 54 and are equidistantly spaced with respect to each other and arranged in an annular series about the axis of the dial, and similar openings 71 are formed in the dial 57 and may be brought to position opposite the openings 70. A pair of studs 72 is provided upon the rear face of the flange 66 of the finger knob 65 and these studs are arranged to project through the openings 71, there being but two of said openings in the dial 57 and the ends of these studs terminate short of the plane of the front face of the said dial 54. Normally, therefore,

there is no connection between the dials 54 and 57 and, therefore, the dials may rotate inde endently of each other. However, when it Is desired to rotate the dials in unison so as to quickly adjust the same without resorting tov adjustment through the tedious and continuous rotation of the vernier knobs 39 and 47 for a considerable period of time, the finger knob 65 is grasped and pressed inwardly thus efiectingengagement of the ends of the studs 72 in the openings 7 0 in the'dial 54, the knob 65 being so rotated, at this time, as to rotate the dial 57 to a position where its openings 71, and consequently the ends of the studs 72, will be opposite a pair of the openings 70. In this manner, the two di'als are connected for rotation in unison, anda further rotation of the knob 65 will effect such denser units, it will be understood that three so ial housing 35 is formed centrally with an or more units may be employed if desired. movement of the knob against the tension of Having thus described my mvention, what said spring. I claim as new is 1. A variable condenser comprising a plu- HENRY SPONGBERG. 5 rality of units, each embodying a stator and a rotor, venier means for independently adjustingthe rotors of the units, the said rotors of the unitsembodying concentrically arranged shafts, dials upon the shafts, the said dials being provided with openings adapted to be brought opposite to each other in the relative rotativeadjustmentpf the dials,'a rotatable knob having projections engaging through the openings in one of the dials the said knob being shifable to effect engagement of the said members in the openings in the other dial, and means yieldably holding the knob in inactive position.

2. A variable condenser comprising a plurality of units, each unit embodying a stator 'and a rotor, Vernier means for independently adjusting the rotors of the units, the rotors of the units embodying concentrically arranged shafts, dials upon the shafts, andmeans coacting with one of the dials and openable to rotate said dial inde endently of the other dial and independently of the vernier means and adjustable to coact with the said other dial to effect adjustment of the so dials in unison independently of said Vernier means.

3; A variable condenser comprising a plurality of units, each embodying a stator and a rotor, Vernier means for independently adjusting the rotors of the units, meansoperatively connected with the rotor of each unit for adjusting the respective rotor, and means associated with the adjusting means for the rotor of one unit and ope'rablej to adjust the 40 rotor independently of the Vernier means and adjustable to coact with the adjusting means for the rotor of the other-unit to actuate the same simultaneously with the first mentioned rotor adjusting means. 41 A-variable condenser comprising a plurality of units each embodying a stator and a rotor, Vernier means for independently adjusting the rotors of the units, the said rotors of the units embodying concentrically arranged shafts, dials upon the shafts, a casing enclosing the dials and having a sight opening opposite the peripheral portions of the dials, a knob rotatably mounted in the front wall of the casing and having a head located within the casing, a spring upon one of said shafts yieldably holding the knob in position with 1ts head engaging against the said front of the casing, the said' dials being provided with openings adaptedfto be brought opposite to :ach other in the relative rotative adjustment of the dials,'and studs upon the head ofthe knob projectin into the openings in one of the dials and a apted to be projected into the openings in the other dial to connect the two dials for rotation in unison upon the inward 

